1. Field of the Invention
The present invention relates to an electric vehicle mirror apparatus provided with a rotation driving unit to rotate a housing, and more particularly, to a vehicle mirror apparatus having an improved structure which supports rotation of the housing.
2. Description of the Related Art
A conventional electric vehicle mirror apparatus, one disclosed in Japanese Patent Application Laid-open No. Hei-7-329642 is known. This vehicle mirror apparatus includes a mirror base fixed to a vehicle body, a stationary shaft holder integrally formed on the mirror base, and a housing rotatably mounted on the shaft holder.
The shaft holder is integrally formed with a shaft, and the shaft penetrates the housing so that the housing rotates around the shaft. The housing has a mirror unit including a mirror. The housing accommodates a motor which rotates the housing, and a reduction gear transmitted to an output shaft of the motor. The housing and the mirror unit integrally rotate between a using position and an accommodated position by driving of the motor.
FIGS. 1 and 2 show a structure for supporting the rotation of the housing. In FIG. 1, a reference numeral 100 represents a shaft holder formed on a mirror base (not shown). The shaft holder is integrally formed with a hollow shaft 110. A reference numeral 130 represents the housing which rotates around the shaft 110. A motor and a reduction gear (both not shown) are accommodated in the housing.
A large-diameter is set to be a root portion 120 of the shaft 110, and the root portion 120 is fitted into a shaft holding portion 140 of the housing 130, thereby supporting the rotation of the housing 130. By setting the large-diameter to be the root portion 120, a large contact area between the root portion 120 and the shaft holding portion 140 can be secured, and this makes it possible to stably rotate the housing 130.
FIG. 2 is a plan view of the root portion 120 and the shaft holding portion 100. The shaft holding portion 140 slides over the entire peripheral surface of the root portion 120 having a circular outer surface in a state where the shaft holding portion 140 is in contact with the entire peripheral surface of the root portion 120, thereby supporting the rotation of the housing 130.
According to the conventional rotation supporting structure of the housing 130, since the root portion 120 of the shaft 110 and the shaft holding portion 140 of the housing 130 are in contact with the entire peripheral surface of the root portion 120, the sliding resistance is great. Therefore, there are problem is that it is necessary to increase output which rotates the housing 130, a motor which rotates the housing 130 is increased in size, and it is difficult to reduce the entire vehicle mirror apparatus both in size and weight.
If the diameter of the root portion 120 of the shaft 110 is increased in order to strongly support the rotation of the housing 130, since the sliding resistance caused when the housing rotates becomes great, it is necessary to increase the output which rotates the housing. The conventional technique also has a problem that since the rotation supporting force of the housing 130 and a rotating force are conflicting with each other, it is difficult to adjust these forces.